Definite Time, High-Set Elements 50-3, 50-2, 50N-3, 50N-2 - Siemens SIPROTEC 4 User Manual

Functions
2.2 Overcurrent Protection 50, 51, 50N, 51N

Definite Time, High-set Elements 50-3, 50-2, 50N-3, 50N-2

2.2.2
For each element, an individual pickup value 50-3 PICKUP, 50-2 PICKUP or 50N-3 PICKUP, 50N-2
PICKUP is set. For 50-3 PICKUP and 50N-3 PICKUP, it is possible to measure the Instantaneous in
addition to Fundamental and True RMS. If set to Instantaneous, the element picks up at 2 · √2 · setting
value (rms). Each phase and ground current is compared separately per element with the common pickup
values 50-3 PICKUP, 50-2 PICKUP or 50N-3 PICKUP, 50N-2 PICKUP. If the respective pickup value is
exceeded, this is signaled. After the user-defined time delays 50-3 DELAY, 50-2 DELAY or 50N-3 DELAY,
50N-2 DELAY have elapsed, trip commands are issued which are available for each element. The dropout
value is roughly equal to 95% of the pickup value for currents > 0.3 Ι
neous values has been parameterized for the 50-3 or 50N-3 element, the dropout ratio is set to 90 %.
Pickup can be stabilized by setting dropout times 1215 50 T DROP-OUT or 1315 50N T DROP-OUT. This
time is started and maintains the pickup condition if the current falls below the threshold. Therefore, the func-
tion does not drop out at high speed. The trip delay time 50-3 DELAY, 50-2 DELAY or 50N-3 DELAY,
50N-2 DELAY continues running in the meantime. After the dropout delay time has elapsed, the pickup is
reported OFF and the trip delay time is reset unless the threshold 50-3 PICKUP, 50-2 PICKUP or 50N-3
PICKUP, 50N-2 PICKUP has been exceeded again. If the threshold is exceeded again during the dropout
delay time, the time is canceled. The trip delay time 50-3 DELAY, 50-2 DELAY or 50N-3 DELAY, 50N-2
DELAY continues running in the meantime. If the threshold value is exceeded after this time has elapsed, the
trip command is issued immediately. If the threshold value is not exceeded at this time, there is no reaction. If
the threshold value is exceeded again after expiry of the trip command delay time while the dropout delay
time is still running, tripping is initiated immediately.
These elements can be blocked by the automatic reclosing function (79 AR).
The following figures give an example of logic diagrams for the high-set elements 50-2 PICKUP or 50N-2
PICKUP. They also apply analogously to the high-set elements 50-3 PICKUP and 50N-3 PICKUP.
58
. If the measurement of the instanta-
Nom
SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016